The present invention relates to a feedback control method and apparatus for a polyphase electric motor.
There exists an electric motor that performs vehicle driving (traction) and vehicle braking (regeneration). By developing vector control technology, various kinds of electric motor control have become possible to be performed accurately and smoothly. Therefore, recently, using a polyphase alternating-current motor, such as a polyphase induction motor or a permanent magnet synchronous motor, for wheel drive motor control is performed using vector control technology. Japanese Patent Application Publication No. JP-A-2005-192341 discloses a permanent magnet synchronous motor mounted in a hybrid vehicle, and Japanese Patent Application Publication No. JP-A-2006-14539 discloses a vector control of this kind of motor.
For example, a three-phase permanent magnet synchronous motor is provided with a rotor equipped with a permanent magnet, and a stator equipped with stator coils of U-phase, V-phase, and W-phase. Japanese Patent Application Publication No. JP-A-2006-14539 describes a drive control apparatus for making the motor generate drive motor torque, which is torque of a drive motor, or generator torque, which is torque of a generator. The control apparatus sends pulse width modulation signals (PWM pulses) of U-phase, V-phase, and W-phase to an inverter. With the inverter supplying phase currents, namely U-phase, V-phase, and W-phase currents, to respective stator coils, the drive motor torque or the generator torque is generated.